If a message is not found in Microsoft 365 Message Trace, there could be several reasons for this issue:
Message Hasn’t Reached Microsoft 365: The message may not have reached the Microsoft 365 environment yet. This can happen if there are delays in the email routing or if the message is still in transit.
Search Criteria: The search criteria you entered may not match the message you’re looking for. Ensure that you’ve entered the correct sender, recipient, date range, or other relevant filters.
Retention Policy: If the message is older and has been deleted based on your organization’s retention policies, it may no longer be available in Message Trace.
Hybrid Deployments: In hybrid environments where you have a combination of on-premises Exchange servers and Exchange Online (Microsoft 365), Message Trace may not cover on-premises email flows. You may need to check your on-premises message tracking logs separately.
Message Trace is a powerful tool that is essential for any IT administrator who is responsible for managing email infrastructure.